This invention relates to wave energy converter (WEC) devices and WEC buoys (systems) which are configured to produce power efficiently in response to waves whose periods (or wavelengths) may vary substantially as a function of time.
Certain WEC devices are designed to be most efficient in response to high-amplitude, long-period waves. These WEC devices are designed to be primarily responsive to up-down (heave) motion of the waves. The “heave” driven WEC devices tend to be inefficient in response to short period waves causing pitching.
Other WEC devices are designed to be more efficient in response to short period waves which tend to cause pitching (or rolling) of the WEC devices. But these “pitch driven” WEC devices tend to be inefficient in response to long period waves which cause the WEC buoy to primarily move up and down (heave).
Using a primarily (or only) heave responsive WEC device when the periods of the waves may be characterized as “short” is inefficient and not satisfactory. Likewise, using a primarily (or only) pitch responsive WEC device when the periods of the waves may be characterized as “long” is also inefficient and not satisfactory.
It is therefore desirable to have a WEC system which can produce power efficiently as the periods of the waves vary over a wide range; i.e., as the periodicity of the waves vary between “long” and “short”.
It is also desirable to have WEC devices which can be efficient in response to heave and/or pitch motion to produce a substantial amount of power efficiently as the periods of the waves vary over a wide range.